Gripping mechanism



June 21, 1938.

w. w. CRILEY I 2,121,119

GRIPPING MECHANISM Filed Feb. 9, 1957 3 Sheets-Sheet l INVENTOR W/LL/AM M/ C /LEY June 21, 1938. w w, CRILEY 2,121,119

GRIPPING MECHANISM Filed Feb. 9, 1937 v 3 Sheets-Sheet 2 INVENTOR l'V/Ll/AM 1 CR/LEY June 21, 1938. w. w. CRILEY 2,121,119

GRIPPING MECHANISM Filed Feb. 9, 195"! 5 Sheets-Sheet 5 I 1 B g & INVENTOR.

Patented June 21, 1938 UNITED STATES 6 Claims.

This invention relates to an improvement in forging machines which commonly employ stock gripping dies for firmly holding a stock blank in a fixed position while the heading die acts upon the blank, and is particularly directed to the mechanism for operating the stock gripping dies and for relieving excess stresses resulting from gripping oversize stock so as to protect the frame of the machine and gripping die closing mechamsm.

An important object of this invention, therefore, lies in the provision of a gripping die operating mechanism which occupies a minimum amount of space Without sacrificing the capacity or forging range, the strength of the parts, or the efficiency of operation, as a result of which construction the use of shorter and less costly frames than have heretofore been possible and accordingly a machine which is extremely rugged and compact are provided.

A correlative object is to provide, in a forging machine of this character, an operating mechanism having a laterally floating cross head member directly connected to the main gripping toggle mechanism, as a result of which floating connection, the usual intermediate link between the cross head and main gripping toggle is eliminated.

An equally important and more specific object is to provide, in a stock gripping die operating mechanism, a safety release which yields when the gripping pressure of the dies upon the stock blank exceeds a certain predetermined maximum magnitude and prevents the transmission of excessive lateral stresses to the frame and. other working parts of the machine and thereby eliminates the danger of breaking, permanently bending, or otherwise damaging the parts.

Other objects and advantages of the invention will become apparent from the following'description and accompanying drawings.

In the drawings- Fig. 1 is a plan View of the die operating mechanism showing the dies in extreme open position;

Fig. 2 is a side elevation of the various links, levers and bell cranks comprising the die operating mechanism in the position corresponding to Fig. 1;

Fig. 3 is a planview similar to Fig. 1, showing the dies gripping an oversized blank of stock;

Fig. 4 is a view similar to Fig. 2, showing the safety release feature functioning the positions of the levers, etc., corresponding to those in Fig. 3;

Figs. 5 and 6 show different positions of the floating cross head member; and

Figs. '7 and 8 are side elevations of a modification of theinvention.

Referring to the drawings, the invention is shown in connection with a forging machine which comprises a frame i on which is mounted the usual header die 2, and cooperating stationary and movable stock gripping dies 3 and d, respectively. The dies 2 and are each constrained to move in predetermined paths between suitable guiding surfaces in the frame. The header die 2 is reciprocally driven from a suitable eccentric on a main crank shaft 6 through the medium of a connecting rod l in a well known manner. The movable stock gripping die i, however, is reciprocally driven from the same crank shaft 5 through an operating mechanism, about to be described.

The gripping die operating mechanism comprises an eccentric pin it preferably mounted on a disk ll which is rigidly mounted on one end of the crank shaft ii for rotation therewith. A crank arm i2 is pivctally joined atone of its ends to the crank pin iii, the opposite end of the crank arm 52 being pivotally secured by a suitable pin to one arm it of a bell crank Hi. The bell crank it is mounted for rocking movement on a pivot pin ll which, in those instances in which a safety release is employed, may be mounted on a movable support, as will later be described. Thus, as the crank shaft E and crank pin l!) rotate, the crank arm l2 oscillates the bell crank it about its pivot pin ii. The other arm l 3 of the bell crank it is connected to one end of a connecting rod 20 through the medium of a spherical joint such as a ball and socket connection 22 shown in Figs. 1 and -3,the purpose of which will hereinafter be described.

This oscillating motion of the bell crank it imparts reciprocating motion to a cross head member 24 which is connected to the opposite end of the connecting rod 2d by a wrist pin 25. The cross head 2% is provided with flat top and bottom sliding surfaces 2"! and 28, respectively, which are engaged by flat bearing surfaces 29 and 30, respectively, on the frame i.

It will be noted that the cross head 24'. is not guided laterally by surfaces on the frame as is customary in prior machines but is free to float transversely of the frame a limited amount during its reciprocating movement between the bearing surfaces 29 and til.

This free laterally fioatingfeature of the cross head 24 permits the forward end thereof to be directly and pivotally connected to a pair of main gripping toggle links 33 and 34 by the knuckle pin 35.

In prior machines of this character wherein the cross head is guided vertically and horizontally for movement in a rectilinear path, an intermediate link is provided between the forward end of the cross head and the knuckle pin of the gripping toggle links to compensate for the swing of the knuckle end of the toggle link 33 about its stationary pivot pin. Consequently, these machines require a frame which is from several inches to several feet greater in length than a machine embodying the present invention, which eliminates the necessity of the intermediate link without altering the capacity of the machine, the strength of the parts, or the efficiency of operation.

The toggle link 33 is pivotally mounted on the frame I by a stationary pin 31 which is rigid with the frame and located at one side of the plane of movement of the bell crank l6. Thus the forward end of the cross head 24 moves in an arcuate path defined by the swinging knuckle end of the toggle link 33 which carries the knuckle pin 35.

Toggle link 34 is normally angularly disposed to toggle link 33 and is pivotally connected by a pin 38, which is located on the opposite side of the plane of movement of the bell crank, to a member which reciprocates laterally of the frame and carries and actuates the movable stock gripping die 4 toward and away from the stationary gripping die 3.

In operation, the cross head 24 is moved generally forwardly from the position shown in Figs. 1 and 2 to the position indicated in Figs. 3 and 4 by the mechanism described above. Since the forward end of the cross head is pivotally connected to the knuckle ends of the toggle links 33 and 34-by the common knuckle pin 35, and since the toggle link 33 is pivotally fixed to the frame I, it follows that the forward movement of the cross head spreads the angle between the two toggle'links 33 and 34 and causes the member 40 and die 4 to move toward the stationary die 3.

In order to compensate for the slight lateral movement of the cross head relative to the plane of movement of the arm l8 of the bell crank l6 as the head follows the arcuate path defined by the pin 35, the connecting rod 20 is secured at one of its ends to the bell crank arm I8 by the spherical bearing connection 22. This spherical bearing connection or ball joint permits the end of the connecting rod 20, which carries the wrist pin 25, to swing laterally with the cross head 24 when driving the same while the other end of the rod 20 is constrained to move in the plane of the bell crank arm [8.

It is by means of this ball joint 22 and in conjunction with the laterally floating cross head 24 that the cross head may be secured directly to the toggle links 33 and 34 and thus eliminate the customary intermediate link and accordingly permit the construction of a frame and machine which is shorter, more compact, and less expensive than prior machines of the same capacity.

In forging machines employing stock gripping dies, which rigidly grip and hold the blanks during the forging operation, it has been found desirable to provide a safety release mechanism 'for the purpose of limiting the gripping pressure when the stock is oversize or when the gripping mechanism contacts some other obstruction, and consequently limiting the stress on frame and working parts of the machine to a predetermined safe maximum magnitude.

Broadly, the mechanism provides a yieldable support for the pivot pin Il heretofore referred to and which pin carries the bell crank 16. Thus, when the gripping pressure exceeds the said predetermined safe maximum magnitude, the reaction of such pressure, which is carried by the parts of the die operating mechanism, causes the normally fixed pivot pin I! to yield toward the rear of the machine, thus allowing the crank arm l2 and its eccentric pin it to complete the operating cycle Without any danger of overstressing or breaking the parts.

As shown in Figs. 2 and 4, this pivot pin I! is mounted on a lever 50 which in turn is pivotally supported on the frame I by a suitable pin 5|. In efiect, the pin [1 amounts to a crank pin with respect to the pivot 5| so that a suflicient force applied to the pin I! through the dies, rod 20, and crank I6, would move the said pin I? from its normal position and cause the lever 50 to swing about its pivot 5|.

The normal position of the pin i1 is determined by an abutting surface 54 on the lever 50, which abutting surface is held in pressure engagement against a stop 55 on the frame I. In order for the pivot pin H to move or yield from its normal position, the force tending to so move the said pivot pin must necessarily overcome the force producing the pressure engagement of the abutting surface 54 against the stops 55.

In the illustrated construction, the pressure engagement of the abutting surface 54 and stop 55 originates from a force produced by a spring 51, which force is preferably amplified through the medium of a series of links and levers to effect a heavy yet yieldable pressure engagement of the abutment against the stop.

The linkage which transmits the force from the spring 51 to the abutment 54, as illustrated in the drawings, comprises a link 60 pinned at one end to the lever 50 preferably near the zone of the abutting surface 54, the other end of said link 60 being pivotally secured to one arm of a bell crank member 62. This bell crank 62 is mounted on the frame I for limited rocking movement relative thereto by a pivot support 63. It will be noted from Fig. 2 that the line of action of the force producing the pressure engagement between the abutting surfaces 54 and the stop 55 lies slightly to one side of the axis of the pivot support 63 so that a tremendous seating force is developed by the spring 51. This seating force requires a very large reacting force on the pivot I! to swing the lever 50 away from the stop 55 and cause the bell crank 62 to rock in a given direction about its pivot 63. Due to the much longer lever arm from the pivot 5| to the stop 54, compared to the arm from the pivot 5| to the pin I1, an additional mechanical advantage is obtained. The other arm of the bell crank 82 has secured thereto a shackle link 64 which is connected to one arm of a lever 65 which is also mounted on the frame I for limited rocking movement by a pin 66.

This lever 65, shackle link 64, and bell crank 62 are each normally yet yieldably held in a definiteposition by the action of the compression spring 51 on an eye bolt 68, which eye bolt is secured to the opposite arm of the said lever 65 from the link 64.

The definite normal position which the aforesaid lever, link and bell crank assume is determined by a fixed auxiliary stop 10 on the frame I, against which an associated auxiliary abutting surface ll on the bellcrank 62 reacts. The normal position between the lever 65 and the shackle link 54 is such that the line of force transmitted by the bell crank 62 tending to separate the abutting surface H from the stop Iii lies slightly to one side of the axis of the pin 66 so that, in the event the said force overcomes the force produced by the spring 51, the lever 65 will always rock or yield in the same direction on its pivot 66 so as to act against the force of the spring.

Fig. 4 shows the safety release mechanism in operation with the abutments in separated position. When the force producing the separation of the abutments 54 and H from their respective stops 55 and 10 has been removed, the spring causes the lever, bell crank, and link to again assume their normal relative positions as shown in Fig. 2.

The sole purpose of the members which connect the lever 50 to the spring 5'! is to obtain a mechanical advantage or leverage so that the size spring employed is not unreasonably large. Thus, the normal force acting against the stop 55 is several times greater than the magnitude of the force exerted directly by the spring 51.

Figs. '7 and 3 disclose another form of the safety mechanism, the essential differences over the previously described structure being that the abutments, stops and compression spring are positioned somewhat differently.

It will be noted that in this modification, the crank shaft 6, crank pin [0, crank arm I2,'bell crank it, connecting rod 20 and cross head 2d are substantially the same as in the previously described form. The pivot pin I! which carries the bell crank it is mounted on a lever 80 which is equivalent to the lever 50 in the previously described construction. This lever 80 is mounted for limited rocking movement on a fixed pivot 8! rigid with the frame I of the machine, which pivot is preferably located substantially near the mid-point of the lever 80.

Adjacent the pin i1 and on the lever 80 is an abutting surface 82 which normally engages a stop 83 formed on the frame of the machine. The abutment 82 is held in heavy pressure engagement against the stop 83 by a compression spring 85, the force of which is highly amplified through the medium of a linkage mechanism about to be described.

The spring 85 surrounds an eye-bolt or rod 86 and reacts between a stationary abutment 8? on the frame and an abutment 88 provided on one end of the rod 86. The opposite end of the rod 86 is pivotally secured to one arm of a bell crank 86 which is mounted for limited rocking movement about a fixed pivot 91 rigid with the frame. The other arm of the bell crank 90 is operatively connected to the lever 80 through the medium of a shackle 92. This shackle is secured to the lever 80 on the opposite side of its pivot pin 8| from the pin ll.

The shackle 92 is shown provided with an abutting surface 93 which normally engages a stop 94 preferably on the lever 80. The abutment and stop definitely fix the normal relative positions of the lever 30, shackle 92 and bell crank 9i! so that when the force, acting against the pin I1 and tending to separate the abutment 82 from the stop 83, exceeds the pressure therebetween produced by the spring 85, the bell crank 90 will be caused to rock about its pivot Si in a direction to compress the spring 85.

In this construction, the laterally floating cross head may be employed as Well as the linkage interposed between the cross head and the movable die which have been fully described above.

From the foregoing description, it will be seen that by the direct connection of the laterally floating cross head 24 to the swinging ends of the toggle members 33 and. 34, a considerably shorter and more compact frame can be employed. Furthermore, the invention provides a novel safety feature which protects the frame of the machine as well as the die operating parts from becoming overstressed on occasions when the dies close upon an oversized stock blank. In both forms of the safety feature device, it will be noted that the linkage which connects the springs 51 and 85 to the levers 5i] and 80, respectively, is arranged so that theforce produced by the spring is amplified many times in order to effect the necessary pressure engagement between the abutting surfaces and their associated stops.

Although two forms of the present invention have been shown and described, it will be apparent to those skilled in the art that other forms may be made to accomplish the same purpose without departing from the spirit and scope of the present invention as defined in the hereunto annexed claims.

Having thus described my invention, what I claim is:

1. In a forging machine including a pair of dies mounted for relative movement toward and away from each other in a linear horizontal path, a toggle joint pivotally connected at one end to a movable one of the dies by an upright pivot and pivotally connected at the other end to a fixed upright pivot, a cross head directly connected to the knuckle pin of the toggle joint for swinging in a horizontal plane about the pin axis, slide surfaces supporting said cross head for floating planar sliding movement relative to the surfaces in a horizontal plane, a connecting rod for moving the cross head generally endwise to cause expansion of the toggle joint, said connecting rod being pivotally connected at one end to the cross head by a horizontal pivot, a driving member for operating the connecting rod,

said driving member being movable relatively toward and away from the toggle joint in a fixed vertical plane extending generally parallel to the length of the cross head, and a universal connection between the other end of the connecting rod and the driving member, whereby the cross head and the connecting rod may move laterally of its general endwise path of travel for compensating for the curvilinear path of the knuckle pin.

2. In a forging machine, a mechanism for opening and closing a pair of dies which are movable relatively toward and away from each other in a linear horizontal path by breaking and expanding a toggle joint which is pivotally connected at one end to one of the dies by an upright pivot and pivotally connected at its other end to a fixed upright pivot and comprising a cross head connected to the knuckle pin of the toggle joint for swinging about the pin axis, horizontal top and bottom guides slidably supporting the cross head for floating planar horzontal movement, a connecting rod pivotally connected at one of its ends to the cross head by a horizontal pivot, a driving member movable toward and away from the path of the dies in a fixed vertical plane which extends generally at an angle to the path of the dies, and a universal connection between the other end of the connecting rod and the driving member.

3. In a forging machine including a pair of dies mounted for sliding movement relatively toward and away from each other in a linear horizontal path, a toggle joint pivotally connected at one end to a movable one of the dies by an upright pivot and pivotally connected at the other end to a fixed upright pivot, a cross head connected to the knuckle pin of the toggle joint for swinging about the pin axis, means slidably supporting the cross head for floating planar sliding movement in a horizontal plane, a connecting rod pivotally connected by one end to the cross head by a horizontal transverse pivot, a cross head driving member movable relatively toward and away from the toggle joint in a fixed vertical plane extending generally at an angle to the path of the dies, a universal connection between said driving member and the other end of said connecting rod, whereby the cross head and connecting rod may move in an arcuate path to compensate for. the curvilinear travel of the knuckle joint pin as the toggle joint is expanded, a driving crank shaft, link mechanism operatively connecting said driving member to the crank shaft, means supporting said driving member for bodily movement in said vertical plane away from the path of the dies and from its normal operating position, and means yieldably opposing said bodily movement.

4. In a forging machine, including a die closing mechanism having a cross head mechanism movable in one direction along a given path for closing the dies, a driving bell crank member operatively connected with said cross head mechanism and arranged for oscillation to apply force in said direction to the cross head mechanism for moving the cross head mechanism in said direction consequent upon rocking of the bell crank about its pivotal axis, a carrier member movable in an opposite direction in a path generally parallel to the plane of oscillation of the bell crank and pivotally supporting the bell crank, means connected to the carrier member and yieldably opposing movement thereof in said opposite direction, and means for driving the bell crank member.

5. In a forging machine including a die closing mechanism movable along a given path in a die closing direction, a support, a bell crank operatively connected with the mechanism and.

pivotally connected to the support between the ends of the support for oscillation about a horizontal pivot extending transversely of the path of travel of said mechanism, said bell crank being operative for moving the mechanism in said direction consequent upon oscillation of the bellcrank in one direction about its pivotal axis, said support being mounted near one of its ends for swinging movement opposite to the die closing direction about a horizontal pivot extending parallel to the pivotal axis of the bell crank and spaced therefrom, whereby upon oscillation of the bell crank for moving said mechanism in said die closing direction, said support swings about its pivot in the opposite direction, resisting means operatively connected to said support near its other end and yieldably opposing movement of 1 said support in said opposite direction, and means for oscillating the bell crank.

6. In a forging machine including a die closing mechanism movable along a given path in a die closing direction, a support, a bell crank operatively connected with the mechanism and pivotally connected to the support between the ends of the support for oscillation about a horizontal pivot extending transversely of the path of travel of said mechanism, said bell crank being operative for moving the mechanism in said direction consequent upon oscillation of the bell crank in one direction about its pivotal axis, said support being mounted near one of its ends for swinging movement opposite to the die closing direction about a horizontal pivot extending parallel to the pivotal axis of the bell crank and spaced therefrom, whereby upon oscillation of the bell crank for moving said mechanism in said die closing direction, said support swings about its pivot in the opposite direction, resisting means operatively connected to said support near its other end and yieldably opposing movement of said support in said opposite direction, and a driving link for oscillating the. bell crank and having its line of action at all times between the pivotal axis of the bell crank and the point of application of the force of the resisting means.

WILLIAM W. CRILEY. 

